Isonitriles are the only class of stable organic compounds containing formally divalent carbon. The terminal carbon adjacent to the nitrogen behaves as an electrophile and/or a nucleophile during reactions. The unique reactivity of this divalent carbon accounts for the wide variety of reactions, particularly multicomponent reactions, and makes them useful intermediates for the synthesis of a wide variety of compounds. Reactions involving phosgene methods are now most widely used for the preparation of isonitriles. Due to the high toxicity of phosgene, an alternate, convenient, and high yield method would be very desirable. Powers, J. C.; Seidner, R.; Parsons, T. G.; Berwin, H. J. J. Org. Chem. 1966, 31, 2623. report the reaction of formimidates with sodium hydride gave amidine as the only isolable product. Koga, N.; Koga, G.; Anselme, J.-P. Tetrahedron Lett., 1970, 3309. report attempts to prepare isonitriles by the .alpha.-elimination of the elements ROH from formimidate derivatives by reaction with alkyllithium and triphenylmethyllithium. Reported isonitrile yields were only from trace amounts to 20% and the authors noted that "Exploratory attempts to make this approach a useful isonitrile synthesis were not rewarding."
Pornet, J.; Miginiac, M. L. Tetrahedron Lett., 1971, 967. report yields of 45% and 60% from reaction of ethyl N-(4-methoxyphenyl)formimidate and ethyl N-phenylformimidate with the aminomagnesium reagent [(CH.sub.3).sub.2 CH].sub.2 N-MgBr.